The present invention relates to noise reduction. In particular, the present invention relates to removing noise from speech signals.
A common problem in speech recognition and speech transmission is the corruption of the speech signal by additive noise. In particular, corruption due to the speech of another speaker has proven to be difficult to detect and/or correct.
Recently, a system has been developed that attempts to remove noise by using a combination of an alternative sensor, such as a bone conduction microphone, and an air conduction microphone. This system estimates channel responses associated with the transmission of speech and noise through the bone conduction microphone. These channel responses are then used in a direct filtering technique to identify an estimate of the clean speech signal based on a noisy bone conduction microphone signal and a noisy air conduction microphone signal.
Although this system works well, it tends to introduce nulls into the speech signal at higher frequencies and also tends to include annoying clicks in the estimated clean speech signal if the user clacks teeth during speech. Thus, a system is needed that improves the direct filtering technique to remove the annoying clicks and improve the clean speech estimate.